The Isolation,Identification Of ESBLs-producing Escherichia Coli From Chicken Feces In Changchun And The Analysis Of Its Major Drug Resistant Genes

With the increasing scale and intensive cultivation of modern farming,the rational use of veterinary antibiotics has attracted wide attention.In the chicken industry,the abuse of antibiotics,especially the large-scale use of third-generation cephalosporins resulted in the increasingly severe resistance of chicken-derived extended-spectrum beta-lactamases?ESBLs?to Escherichia coli?E.coli?,which restricts the clinical antibiotics use of veterinarians and is severely harmful to the health of human beings.Therefore,it is particularly important to study the resistance of ESBLs-producing E.coli isolated from chickens and to explore its influence on public health.In this study,115 strains of ESBLs-producing E.coli were isolated and identified from 200chicken feces samples collected from 10 chicken farms around Changchun,Jilin Province.22kinds of drugs,such as?-lactams and aminoglycosides were selected to study the drug-resistant phenotypes and the existence of multi-drug-resistant strains of the isolated strains,and the current situation of different scale farms was analyzed.The results showed that the poorer the production management level,the more serious the drug use,and the higher the detection rate of ESBLs-producing E.coli in chicken feces samples.The isolates were completely resistant to ampicillin,cefazolin and ceftriaxone,and sensitive to both nitrofurantoin and meropenem.Resistance rates to cefotaxime,aztreonam,amoxicillin,ciprofloxacin,enrofloxacin,tetracycline,florfenicol,and cotrimoxazole were all above 50%.The resistance rate to levofloxacin,gentamicin,doxycycline and lincomycin was between 20%to 50%.The isolates maintained good antibacterial activity against amikacin,azithromycin,polymyxin E,vancomycin,fosfomycin,and the resistance rate was less than 20%in which multi-drug resistant strains accounted for 97.4%and the highest resistant strain was 20 resistant.In 115 ESBLs-producing E.coli strains,a total of 30 transconjugants were selected through conjugation experiments,and the MIC of isolated strains,transconjugants and E.coli J53 was tested respectively on 15 antimicrobial agents.The resistance genes of bla_CTX-M,bla_TEM,bla_SHV,blaOXA,NDM-1,qnr-A,mcr-1,sulI,tet-M and type I,II,III integrase were detected in transconjugated plasmids by PCR.The results showed that the drug-resistant transfer rate of ampicillin,cefazolin,amoxicillin,cefotaxime and cotrimoxazole was 100%,the resistance to ciprofloxacin was 83.3%,to ceftriaxone and chloramphenicol 66.7%,to gentamicin and tobramycin 63.3%,to cefoxitin 53.3%,to polymyxin B and polymyxin E\43.3%,to micacin was 40%,and all zygotes were sensitive to meropenem.The detection rates of conjugate resistance genes were bla_CTX-M?100%?,bla_TEM?80%?,bla_SHV?30%?,bla_OXA?0%?,NDM-1?0%?,and qnr-A?76.7%?,mcr-1?13.3%?,sulI?33.3%?,tet-M?0%?,and notably horizontal transfer was detected in four ESBLs-producing E.coli plasmids with mcr-1 gene.Among the transconjugants,the CTX-M+TEM+qnr-A resistance mode was the highest?23.3%?.The type I integrase gene was widely distributed in the conjugate plasmids,and the detection rate was76.7%.The type II and type III integrase genes were not detected.